Configure Prettier as formatter

Author: k4m4

.prettierignore

@@ -0,0 +1,5 @@
+node_modules
+artifacts
+cache
+coverage*
+gasReporterOutput.json

.prettierrc.js

@@ -0,0 +1,5 @@
+module.exports = {
+    tabWidth: 4,
+    printWidth: 120,
+    semi: false
+}

package-lock.json

@@ -5,7 +5,8 @@
   "main": "index.js",
   "scripts": {
     "test": "npx hardhat test",
-    "coverage": "npx hardhat coverage"
+    "coverage": "npx hardhat coverage",
+    "format": "prettier --write **/*.sol **/*.js"
   },
   "author": "researchdao",
   "license": "MIT",
@@ -18,6 +19,8 @@
     "ethereum-waffle": "^3.4.0",
     "ethers": "^5.5.3",
     "hardhat": "^2.8.3",
+    "prettier": "^2.5.1",
+    "prettier-plugin-solidity": "^1.0.0-beta.19",
     "solidity-coverage": "^0.7.20"
   }
 }